Early activation of the interleukin-23-17 axis in a murine model of oropharyngeal candidiasis

Candida albicans is an oral commensal yeast that causes oropharyngeal candidiasis (OPC) in immunocompromised individuals. The immunological pathways involved in OPC have been revisited after the interleukin-17 (IL-17) pathway was implicated in fungal immunity. We studied immediate (<24 h) and adaptive (3-6 day) IL-12 and IL-23-17 pathway activation in naive p40(-/-) mice, which lack IL-12 and IL-23 and develop severe, chronic OPC upon oral inoculation with C. albicans. Macrophages from p40(-/-) mice were less efficient than C57BL/6J controls at killing C. albicans in vitro but very low numbers in the oral mucosae of infected C57BL/6J mice suggest that they are not critical in vivo, at least in this strain. Migration of macrophages to regional lymph nodes of infected p40(-/-) mice was impaired; however, dendritic cell migration was not affected. Recombinant IL-12 therapy provided only temporary relief from OPC, suggesting that IL-23 is required for full protection. In C57BL/6J mice, but not p40(-/-) mice, messenger RNAs encoding IL-23p19 and IL-17 were induced in the oral mucosa within 24 h of infection (6 ± 0.6 and 12 ± 2.7-fold). By day 6 of infection in C57BL/6J mice, IL-17A messenger RNA level had increased 5.1 ± 1.8 and 83 ± 21-fold in regional lymph nodes and oral tissues respectively. Ablation of p40 was associated with delayed or abrogated induction of IL-17A pathway targets (monocyte chemoattractant protein-1, IL-6 and macrophage inflammatory protein-2), and a lack of organized recruitment of neutrophils to the infected oral mucosa. Overall our data show that the IL-23-17A axis is activated early in the oral mucosae of immunologically naive mice with OPC.

Identifying the cellular targets of bioactive small molecules with activity-based probes

The renaissance of cell- or organism-based phenotypic assays has made subsequent target identification for bioactive small organic molecules an important aspect of current drug discovery. Among the many strategies available for target identification, derivatizing bioactive small molecules into activity-based probes has the main advantage of determining small molecule-protein interactions directly in the native environment where the target proteins maintain their three-dimensional structures, including all the post-translational modifications, as the discrete small molecular probes usually have better access to intracellular compartments. Thus this chemical platform will not only afford a more precise means of understanding the mechanisms of action for bioactive molecules, but shed light onto the specificity of the bioactive small molecules. Here we will provide an overview of the strategies for the design of activity-based small molecular probes and review their applications for target identification using case studies. Special emphasis is placed on logistic concerns for probe's design as well as recent developments in this field.

Molecular thermodynamic model for DNA melting in ionic and crowded solutions

A molecular thermodynamic model is developed to predict DNA melting in ionic and crowded solutions. Each pair of nucleotides in the double-stranded DNA and each nucleotide in the single-stranded DNA are respectively represented by two types of charged Lennard-Jones spheres. The predicted melting curves and melting temperatures T(m) of the model capture the general feature of DNA melting and match fairly well with the available simulation and experimental results. It is found that the melting curve is steeper and T(m) is higher for DNA with a longer chain. With increasing the fraction of the complementary cytosine-guanine (CG) base pairs, T(m) increases almost linearly as a consequence of the stronger hydrogen bonding of the CG base pair than that of adenine-thymine (AT) base pair. At a greater ionic concentration, T(m) is higher due to the shielding effect of counterions on DNA strands. It is observed that T(m) increases in the presence of crowder because the crowder molecules occupy a substantial amount of system volume and suppress the entropy increase for DNA melting. At a given concentration, a larger crowder exhibits a greater suppression for DNA melting and hence a higher T(m). At the same packing fraction, however, a smaller crowder leads to a higher T(m).

Long-term exposure to sodium nitrite and risk of esophageal carcinoma: a cohort study for 30 years

The objective of this study is to investigate the risk of esophageal carcinoma in a cohort with long-term occupational exposure to sodium nitrite. The method used was a retrospective cohort study. A small wood screw manufacturer was founded in 1977 and closed down in 2000. In their production process, the sodium nitrite solution was used to serve as anticorrosive and coolant fluid. One hundred sixty workers in turning and milling shops had direct exposure to sodium nitrite through skin, mouth, and airway because of lack of occupational protective knowledge (study group), whereas 255 workers from other workshops without direct contact with sodium nitrite served as control group. The incidence, diagnosis, and treatment of esophageal carcinoma as well as other malignant tumors in these two groups were followed until the end of 2007. The sodium nitrite exposure time in the study group ranged from 16 to 23 years, with an average of 22.1 years. During 30 years of follow-up, there were 11 esophageal carcinomas and 10 other malignant tumors (4 hepatic cell carcinomas, 3 lung cancers, 2 breast cancers, and 1 leukemia) documented in the study group, while no cancer developed in the control group. The risk for esophageal carcinoma was significantly increased in the study group compared with the control group (relative risk = 1.26, 95% confidence interval = 1.08-1.46, chi-square = 116.83, P < 0.001). Long-term exposure to sodium nitrite markedly increases the risk of esophageal carcinoma in human body.

Identification of lobar fissures in pathological lungs

Identification of lobar fissures in human lungs is a non-trivial task due to their variable shape and appearance, along with the low contrast and high noise in computed tomographic (CT) images. Pathologies in the lungs can further complicate this identification by deforming and/or disrupting the lobar fissures. Current algorithms rely on the general anatomy of the lungs to find fissures affected by pathologies. This can be unreliable as deformations and/or disruptions of these fissures will alter the general lung anatomy. To overcome this, we developed an algorithm with the following novelties: (1) a new application of neural network based texture analysis to generalize fissure regions; and (2) a new method of fissure surface identification. We tested our algorithm on CT image stacks from 8 anonymous patients with pathological lungs. Compared to manually segmented fissures, our algorithm produced an average mean difference of 0.71 mm and 0.68 mm for identifying the left and right oblique fissures, respectively. Using a 3-mm percentile measure, the algorithm yielded an average accuracy of 86.8% for the left oblique fissure with a mean worst-case error of 3.18 mm. For the right oblique fissure, the algorithm produced an accuracy of 88.8% with a mean worst-case error of 3.13 mm. The above results show feasibility of using our algorithm for identifying fissures in pathological lungs.

Effect of alendronate on alveolar bone resorption and angiogenesis in rats with experimental periapical lesions

AIM

To investigate the effects of systemically administered alendronate, one of the most potent bisphosphonates (BPs), on alveolar bone resorption and angiogenesis in rats subjected to experimental periapical lesions over two time periods.

METHODOLOGY

Forty adult Sprague-Dawley (SD) rats were divided equally into control and experimental groups, and the pulp chambers of mandibular first molars of all rats were exposed to the oral environment to induce periapical lesions. The experimental group received daily subcutaneous injections of alendronate at a dose of 0.25 mg kg(-1), whereas the control group received only the saline vehicle. These injections were initiated 1 week before the periapical lesion induction and then continued daily throughout the entire experimental period. After 2 or 4 weeks following pulp exposure, the rats were killed, and the mandibles were examined histologically for periapical bone loss area, number of microvascular vessels (NMV) and tartrate-resistant acid phosphatase (TRAP) activity.

RESULTS

Overall, periapical bone loss area and the number of TRAP-positive cells (osteoclasts) were significantly decreased at 2 and 4 weeks, respectively, after daily subcutaneous injection of alendronate compared with the control group (P < 0.05). There was no significant decrease change in NMV (P > 0.05).

CONCLUSIONS

Administration of alendronate to rats might inhibit alveolar bone resorption associated with periapical disease, which might not lead to impairment of angiogenesis. However, because of the differences between rats and humans, one has to consider the possible consequences of this treatment in the clinic.

Transgenic rescue of enamel phenotype in Ambn null mice

Ameloblastin null mice fail to make an enamel layer, but the defects could be due to an absence of functional ameloblastin or to the secretion of a potentially toxic mutant ameloblastin. We hypothesized that the enamel phenotype could be rescued by the transgenic expression of normal ameloblastin in Ambn mutant mice. We established and analyzed 5 transgenic lines that expressed ameloblastin from the amelogenin (AmelX) promoter and identified transgenic lines that express virtually no transgene, slightly less than normal (Tg+), somewhat higher than normal (Tg++), and much higher than normal (Tg+++) levels of ameloblastin. All lines expressing detectable levels of ameloblastin at least partially recovered the enamel phenotype. When ameloblastin expression was only somewhat higher than normal, the enamel covering the molars and incisors was of normal thickness, had clearly defined rod and interrod enamel, and held up well in function. We conclude that ameloblastin is essential for dental enamel formation.

Scalable templated growth of graphene nanoribbons on SiC

In spite of its excellent electronic properties, the use of graphene in field-effect transistors is not practical at room temperature without modification of its intrinsically semimetallic nature to introduce a bandgap. Quantum confinement effects can create a bandgap in graphene nanoribbons, but existing nanoribbon fabrication methods are slow and often produce disordered edges that compromise electronic properties. Here, we demonstrate the self-organized growth of graphene nanoribbons on a templated silicon carbide substrate prepared using scalable photolithography and microelectronics processing. Direct nanoribbon growth avoids the need for damaging post-processing. Raman spectroscopy, high-resolution transmission electron microscopy and electrostatic force microscopy confirm that nanoribbons as narrow as 40 nm can be grown at specified positions on the substrate. Our prototype graphene devices exhibit quantum confinement at low temperatures (4 K), and an on-off ratio of 10 and carrier mobilities up to 2,700 cm(2) V(-1) s(-1) at room temperature. We demonstrate the scalability of this approach by fabricating 10,000 top-gated graphene transistors on a 0.24-cm(2) SiC chip, which is the largest density of graphene devices reported to date.